In electric power transmission and distribution networks, fault current conditions may occur. A fault current condition is an abrupt surge in the current flowing through the network caused by a fault or a short circuit in the network. Causes of a fault may include lightning striking the network, and downing and grounding of transmission power lines due to severe weather or falling trees. When a fault occurs, a large load appears instantaneously. In response, the network delivers a large amount of current (i.e., overcurrent) to this load or, in the case, the fault. This surge or fault current condition is undesirable and may damage the network or equipment connected to the network. In particular, the network and the equipment connected thereto may burn or, in some cases, explode.
One system used to protect power equipment from damage caused by a fault current is a circuit breaker. When a fault current is detected, the circuit breaker mechanically opens the circuit and disrupts overcurrent from flowing. Because a circuit breaker typically take 3 to 6 power cycles (up to 0.1 seconds) to be triggered, various network components, such as transmission lines, transformers, and switchgear, may still be damaged.
Another system to limit a fault current and to protect power equipment from damage caused by a fault current is a superconducting fault current limiter (SCFCL) system. Generally, an SCFCL system comprises a superconducting circuit that exhibits almost zero resistivity below a critical temperature level TC, a critical magnetic field level HC, and a critical current level IC. If at least one of these critical level conditions is exceeded, the circuit quenches and exhibits resistivity.
During normal operation, the superconducting circuit of the SCFCL system is maintained below the critical level conditions of TC, HC, and IC. During a fault, one or more of the aforementioned critical level conditions is exceeded. Instantaneously, the superconducting circuit in the SCFCL system is quenched and resistance surges, which in turn limits transmission of the fault current and protects the network and associated equipment from the overload. Following some time delay and after the fault current is cleared, the superconducting circuit returns to normal operation wherein none of the critical level conditions are exceeded and current is again transmitted through the network and the SCFCL system.
The SCFCL system may operate in a direct electrical current (DC) or an alternating electrical current (AC) environment. If the SCFCL operates in an AC environment, there may be steady power dissipation from AC losses (i.e., superconducting thermal or hysteresis losses), which may be removed by a cooling system. Current leads, typically in the form of wires, are typically used to transmit electrical energy or signals in the SCFCL system. However, traditional current leads used in SCFCL systems that operate in AC typically result in substantial heat loss. As a result, optimizing current lead shape and configuration to minimize heat loss may be an important factor to consider by manufacturers.
Accordingly, in view of the foregoing, it may be understood that there may be significant problems and shortcomings associated with current technologies for current leads used in AC applications.